Consolidate /signup page link logic

This moves logic for determining whether or not to show a "Sign up" page
on /signup (i.e. because the `/` route shows another, non-signup page)
into the AppCfg.SignupPath() method. It also changes various signup
links to use this value.

config/config.go

@@ -183,6 +183,16 @@ func (ac *AppCfg) LandingPath() string {
 	return ac.Landing
 }
 
+func (ac AppCfg) SignupPath() string {
+	if !ac.OpenRegistration {
+		return ""
+	}
+	if ac.Chorus || ac.Private || (ac.Landing != "" && ac.Landing != "/") {
+		return "/signup"
+	}
+	return "/"
+}
+
 // Load reads the given configuration file, then parses and returns it as a Config.
 func Load(fname string) (*Config, error) {
 	if fname == "" {

pages/login.tmpl

@@ -65,7 +65,7 @@ hr.short {
 		<input type="submit" id="btn-login" value="Login" />
 	</form>
 
-	{{if and (not .SingleUser) .OpenRegistration}}<p style="text-align:center;font-size:0.9em;margin:3em auto;max-width:26em;">{{if .Message}}{{.Message}}{{else}}<em>No account yet?</em> <a href="/">Sign up</a> to start a blog.{{end}}</p>{{end}}
+	{{if and (not .SingleUser) .OpenRegistration}}<p style="text-align:center;font-size:0.9em;margin:3em auto;max-width:26em;">{{if .Message}}{{.Message}}{{else}}<em>No account yet?</em> <a href="{{.SignupPath}}">Sign up</a> to start a blog.{{end}}</p>{{end}}
 
 <script type="text/javascript">
 function disableSubmit() {

templates/base.tmpl

@@ -47,7 +47,7 @@
 					{{if not .DisableDrafts}}<a href="/me/posts/"{{if eq .Path "/me/posts/"}} class="selected"{{end}}>Drafts</a>{{end}}
 						{{ end }}
 					{{if and (and  .LocalTimeline .CanViewReader) (not .Chorus)}}<a href="/read"{{if eq .Path "/read"}} class="selected"{{end}}>Reader</a>{{end}}
-					{{if and (and (and  .Chorus .OpenRegistration) (not .Username)) (or (not .Private) (ne .Landing ""))}}<a href="/signup"{{if eq .Path "/signup"}} class="selected"{{end}}>Sign up</a>{{end}}
+					{{if eq .SignupPath "/signup"}}<a href="/signup"{{if eq .Path "/signup"}} class="selected"{{end}}>Sign up</a>{{end}}
 					{{if and (not .Username) (not .Private)}}<a href="/login"{{if eq .Path "/login"}} class="selected"{{end}}>Log in</a>{{else if .SimpleNav}}<a href="/me/logout">Log out</a>{{end}}
 					{{ end }}
 				</nav>